Data for 20 patients showed that the relationship between the PAT index and IR signal, calculated as a ratio between temperature before and during the first 100 sec of occlusion, holds promise to simplify and substantially shorten the procedure of endothelial assessment. Thus, peripheral vascular endothelial function testing with both PAT and IR methods correlates with the presence or absence of Sickle Cell Disease. These data suggest that peripheral vascular endothelial function testing with IR imaging is feasible, and this is an important next step in development of this non-invasive technology capable of identifying, differentiating, and locating peripheral vascular beds with endothelial dysfunction.